In performing immunoassays, it is necessary to have a receptor which specifically recognizes the compound or compounds of interest while having weak or no binding to compounds of similar structure which may be encountered in the samples of interest. In order to obtain antisera, when haptens are involved, it is necessary that derivatives of the hapten be designed for conjugation to an antigen, where the resulting antisera will provide for the desired specificity. In many situations, the hapten of interest is highly functionalized, so that the synethetic procedure for the derivative must be designed to maintain the integrity of the structural features of the haptens.